I should, of course, have said 'symbol of' in my posting above.

"How now shepherd what means that" is in Chappell's PMOT from a garland of 1620. Part of it was incorporated in a similar song on a late 17th century broadside ballad (ZN218) which can be seen on the Bodley Ballads website, "The Shepherd's Lamentation for his Phillis"